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Author Topic:   Evidence for Evolution: Whale evolution
dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


Message 1 of 443 (646052)
01-02-2012 12:36 PM


Whale evolution

One strange creature that we find is the whale. Surprisingly whales are genetically far more similar to other mammals than to fish even though they look like fish. Whales may look like fish on the outside, but they are far different on the inside, and are actually mammals.
Whales have hair, a trait found in mammals not fish. Whales give birth to live young and don't lay eggs like fish. They feed their young with breast-milk which is a mammal trait not seen in fish. Whales have smooth skin not fish scales. Whales move their tails up and down when swimming, a mammal trait. Fish move their tails side to side. Whales have pelvises just like mammals, and have a hand structure in their front fins unlike fish.
The below links show the fish and whale skeletons compared.
The most important feature of all is that whales have lungs instead of gills. This would be comparable to making a monkey with gills instead lungs. This monkey would live and eat up in the trees, but from time to time they will have to rush back in the water to breathe. Dolphins are also mammals that look like fish.
Whales also have a four-chambered stomach which is a super-stomach meant to grind up grass and leaves that most other animals can't really use. However whales don't eat grass or leaves but they do eat tiny sea creatures called krill, and zooplankton. They also eat tiny single-celled algae, fish, squid, shrimp, marine mammals and birds. Of course different whales have different specialized diets. Whales do not need four-chambered cattle stomachs to eat sea creatures, so a four-chambered stomach is very unnecessary. Having a four-chambered stomach is like cutting paper with a chain saw.
This makes sense from an evolutionary view because whales are most related to cattle which eat grass and leaves, and so inherited their stomachs. The closest land-mammals relative of the whale, the hippo lived mostly in the water, exhibiting a life-style maybe very near that of the ancestors of whales, and eats grass.
The reason for this is that millions of years ago, some land animals that lived in shallow water began adapting themselves more and more for water with fins and the like, until they could not live in the water any-more. This is why whales look like mammals dressed up like fish. The hippo a close relative of whales hints at the possible lifestyle of these ancestors.
In fact we find transitional fossils of land animals evolving into whales.

The above image shows the evolution of whales with more whale-like creatures in higher geological strata. This evolutionary series starts out in 50 million year old strata and becomes more and more whale-like as we approach 35 million year old strata. We find these fossils in Pakistan.

The above link shows the skeletons of the transitionals.
Notice how the front arms are becoming reduced as we go into higher strata. Also notice how the back legs disappear and the pelvis becomes small and distant from the spine. Indeed Dorudon has a transitional pelvis between that of a normal mammal and that of a whale. Notice also how the transitionals increase in size over time.
Richard Dawkins on whale evolution
This two minute video shows how the nose of the mammal ancestors of the whale starts moving up the forehead to become the blow-hole of the whale as we look at more and more whale-like fossils.
Looking at the whale pelvis, we see that it is vestigial. It is tiny and just sitting separated from the spine in the whale. Lets take a closer look on this pelvis.

As you see, it still has the femur which is a leg bone. This is an astounding piece of evidence for evolution.
It is doubtful if this pelvis has any function at all, although it might have some minor function. It is vestigial because it has lost its former function (holding the legs solidly).
29+ evidences for evolution and dolphin embryos
Indeed in the above link, we find that some dolphin species still develop leg bugs in embryonic development. What evolution did was keep the leg buds from developing further into legs; in the dolphins. The embryonic evidence is screaming out who the ancestors of whales are.
Evolution and atavisms
Edward t Babinski on whales and atavisms
The most astounding thing of all is that sometimes unlucky whales and dolphins will develop atavistic legs on their vestigial pelvises! Atavisms are traits formed from ancestral genes that were turned off, but through some mutation is turned back on in a descendent. Often these genes will allow something which started in embryonic development (leg buds) to continue to develop and not stop.
Everything about the whale screams of its origins. The fossil record shows the ancestry of the whale. Whales are strong evidence for the theory of evolution.
Edited by dan4reason, : No reason given.
Edited by Admin, : Reduce image width.

Replies to this message:
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dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


Message 4 of 443 (646077)
01-02-2012 8:19 PM
Reply to: Message 3 by Dr Adequate
01-02-2012 4:53 PM


quote:
Looking for references for this, I found the statement "baleen whales have four chambered stomach system", in Tamura, T., Konishi, K., Isoda, T., Okamoto, R. and Bando, T. 2009c. Prey consumption and feeding habits of common minke, sei and Bryde’s whales in the western North Pacific. Paper SC/J09/JR16 presented to the JARPN II review meeting, January 2009. Besides cutting up whales themselves, they reference the following two papers:
* Hosokawa, H. and Kamiya, T. 1971. Some observations on the cetacean stomachs, with special considerations on the feeding habits of whales. Rep. Whales Res. Inst, 23: 91-101.
* Olsen, M. A., Nordy, E. S., Blix, A. S. and Mathiesen, S. D. 1994. Functional anatomy of the gastrointestinal system of Northeastern Atlantic minke whales (Balaenoptera acutorostrata). Journal of Zoology, London, 234: 55-74.
Now exceptio probat regulam, and the fact that they specified baleen whales suggests that this is not true of toothed whales.
Well, dolphins are toothed whales.
Toothed whales.
and... dolphins have three-chambered stomachs. Most ruminants have four chambered stomachs. Others have three.
quote:
Another problem is your assumption that the four-stomached whales don't need four stomachs. Why not? You haven't really demonstrated it; perhaps they do. Algae might be as tough to digest as grass and leaves.
You could rescue your argument by showing that toothed whales gain and then lose this arrangement in embryo, but this might not be true --- even if the four-chambered stomach is the ancestral form, the T.o.E. only permits this, it does not necessitate it.
---
Well, there are many organisms that eat algae and do not have 4-chambered stomachs. For example, some snails eat algae, and some shrimp. Also, some fish eat algae. You don't need a 4-chambered stomach to eat algae.
quote:
You have made no mention of molecular phylogeny and little mention of embryology, both of which are useful lines of evidence. For example, IIRC, baleen whales grow and then lose teeth in embryo.
Well, I can tell that you know more about this than I do. Can you present this evidence with sources? Thanks. I will add it to my collection of evidence.
Thanks for the critique.
Edited by dan4reason, : No reason given.
Edited by dan4reason, : No reason given.

This message is a reply to:
 Message 3 by Dr Adequate, posted 01-02-2012 4:53 PM Dr Adequate has replied

Replies to this message:
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 Message 13 by Dr Adequate, posted 01-05-2012 11:22 PM dan4reason has replied

  
dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


Message 9 of 443 (646655)
01-05-2012 9:36 PM
Reply to: Message 4 by dan4reason
01-02-2012 8:19 PM


RE: TheArtist
quote:
Very interesting topic. I have a few thoughts though.
First of all, I do not agree with the evolutionary diagrams depicting the changes happening over several millions of years. The oldest known DNA found according to http://news.nationalgeographic.com/...070705-oldest-dna.html is 400 000 years old. Thus, even getting the ‘youngest’ organism, Odontocetes’s DNA would not be possible. How can a diagram like this be assumed to be true when there are no DNA records that can prove that the transitions are even remotely related? There are so many different species of animals, you could make infinitely many different transitional diagrams to ‘prove’ that one species evolved into another when in fact evolution would totally disagree that the particular animal evolved in such a way. Mesonychids and Pakicetus for example could be two different and unrelated animals, putting them next to each other in such a diagram does not prove that the one evolved into the other. Off coarse I cannot disprove this either, I just believe that it should not be used in ‘proving evolution’ as there is NO evidence! For unproven facts no information is better than fiction.
There is a strong correlation between anatomy and genetics. In fact the family tree constructed from genetics is very similar to that from morphology.
quote:
Still, you have not provided Dr Adequate with a satisfactory answer in my opinion. It does not mean that if fish or other organisms eat algae and have only one stomach that whales do not need four.
If algae can be digested without a stomach specialised for eating grass and leaves, then why in the world would a ruminant stomach be needed for algae?
quote:
I would be very interested in some reference to evidence that whales do not use their four stomachs.
I never claimed that.
quote:
In closing, if whales have these vestigial stomachs why didn’t they just stay on land where they would have gotten the most nutrition from a fully adapted system for eating grass. Where did this need come from? What was so attractive about the sea?
Maybe the land-resources were getting all eaten by other animals or there was a drought so they took advantage of water resources. Maybe there was too much predation on land, and far less at sea so they adapted to live in the water, and fight in the water.
Hippos are a good example of this kind of lifestyle.

This message is a reply to:
 Message 4 by dan4reason, posted 01-02-2012 8:19 PM dan4reason has not replied

Replies to this message:
 Message 10 by jar, posted 01-05-2012 9:51 PM dan4reason has replied
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dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


Message 11 of 443 (646659)
01-05-2012 10:50 PM
Reply to: Message 10 by jar
01-05-2012 9:51 PM


RE jar:
quote:
Remember that it is unlikely anything happened quickly and that the critters diverged gradually. The important point is that it is divergence of a population into two populations that we are talking about.
Sure, that seems reasonable.

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dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


(1)
Message 14 of 443 (646853)
01-06-2012 9:19 PM
Reply to: Message 13 by Dr Adequate
01-05-2012 11:22 PM


quote:
Thank you.
I think saying that these stomachs are "unnecessary" is too strong a statement, for one thing it might be read by the incautious as meaning that they're vestigial. They're not, and if you cut three of them out of a whale and then sewed it back up it might well impair its digestion.
If I were to make the point, I'd put it something like this:
There seems to be no functional reason why whales should have multiple stomachs rather than some simpler arangement. The absence of such a reason is evidenced in two ways.
First, the presence of multiple stomachs exists across the whale clade, even though ceteceans don't all have the same diet. It would be a remarkable coincidence if multiple stomachs just happened to suit sperm whales eating giant squid, dolphins eating fish, and blue whales eating krill.
Second, we can see that in other groups of fauna with similar diets multiple stomachs are not present: for example a shark or a tuna with the same diet as a dolphin does not share its digestive arrangements.
However, this anatomical feature can readily be explained as part of the evolutionary heritage of ceteceans ...
... etc etc.
I do have to agree with you. I will make sure to revise my language if I use this in future posts. Thanks for the critique.

This message is a reply to:
 Message 13 by Dr Adequate, posted 01-05-2012 11:22 PM Dr Adequate has not replied

  
dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


Message 19 of 443 (646946)
01-07-2012 12:27 PM
Reply to: Message 18 by TheArtist
01-07-2012 11:01 AM


quote:
The Artist writes:
Apparently the pelvis is crucial to a whale's reproductive system.
1: I think you are using too strong a language when you say "crucial." Second you need to back up this whole statement.
I can reasonable admit that maybe the whale pelvis might have some minor function, however, that function is much reduced and is probably different than its original function.

This message is a reply to:
 Message 18 by TheArtist, posted 01-07-2012 11:01 AM TheArtist has replied

Replies to this message:
 Message 25 by TheArtist, posted 01-09-2012 5:24 AM dan4reason has replied

  
dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


Message 20 of 443 (646949)
01-07-2012 12:36 PM
Reply to: Message 17 by TheArtist
01-07-2012 10:35 AM


quote:
TheArtist wrote:
Point taken, however, we are looking at fossils here. A mere outline of these animals. That is a small portion of an animal’s anatomy and these animals can be vastly different otherwise for all we know (organs, skin, hair, eyes etc.).
Of course. No scientist contests that. But bone structure says a whole lot about non-bone structure. And you can see a lot of evolution even with the few traits you do have.
You do not need 100% proof. You just need evidence beyond reasonable doubt.
quote:
Let me rephrase; it does not mean that if fish or other organisms eat algae and have only one stomach that whales do not need four for whatever reason. I’m not saying that they would need four for digesting algae specifically. I mean that all four could be necessary for their lifestyle and environment i.e. not just there because it used to be part of a cow.
So why would the whale need a four-chambered stomach? Why couldn't they have stomachs like sharks, especially the killer whales?
I found out that actually many non-ruminants have multiple-chambered stomachs. Many whales have what is called the rumen which is a tool for digesting cellulose in plants. Cellulose is meant to keep plants strong, and stiff and defy gravity. The rumen is what is unique to ruminants.

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dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


Message 35 of 443 (647377)
01-09-2012 1:01 PM
Reply to: Message 25 by TheArtist
01-09-2012 5:24 AM


quote:
There is a book by Dr. Bergman and Howe called Vestigial organs are fully functional where they apparently explain in detail how these bones are used and that they are important to the reproductive system on pg 71. They also point out that these bones are different in male and female specimens. Unfortunately I do not have this book to give you a direct quote but it sure sounds worth reading. There are numerous references to this book and what it says about the pelvis but I couldn’t find any direct quotations as yet.
Here is another:
"Evolutionists often point to vestigial hind legs near the pelvis. But these are found only in the Right Whale. and upon closer inspection turn out to be strengthening bones to the genital wall." John C. Whitcomb, Early Earth (1988), p. 84.
There might be later studies where these bones were found in other whales as well.
Wrong, there are many other species that have hips e.g. the sperm whale, and the fin whale. The fact that your "author" would make such an incredibly ignorant mistake suggests his or her extreme bias and ignorance on the topic. Because of that, can you please use a better source? However, not all whales do have vestigial hips. This only goes to show how whales can be made without them and still get along just fine.
Now a vestigial organ does not mean this organ is useless, but one whose original function is much reduced. Naturally nearly every body part will have an effect on other parts no matter how vestigial it might be. The hips have most if not all of their original function.
I need some back-up for the claim that the whale pelvis is "vital" for reproduction, if it is at all.

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Replies to this message:
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dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


Message 44 of 443 (647623)
01-10-2012 2:00 PM
Reply to: Message 43 by herebedragons
01-10-2012 9:55 AM


Here is a more comprehensive list of species.

You will probably notice that it is not 100% in order. That is either because the fossil record is not perfect, and because of minor instances of convergent evolution, dating innacuracies, or even instances of backward evolution in individual species (becoming less whale-like). Each transitional is probably not a direct ancestor of whales and probably have some unique characteristics. So we should see a strong general trend (especially with species with a lot of specimens discovered) not an exact trend.
Before I was just showing a general progression, but now lets get picky.
I want to use this image below:

First, the most important dates are when the species start. So lets use that.
Indohyus:
48 MYA (Indohyus - Wikipedia). Keep in mind we do not have a lot of morphological data and specimen of this fossil.
Diacodexis:
55.4 MYA (Diacodexis - Wikipedia).
Heliohyus:
50-46 MYA (http://tech.groups.yahoo.com/group/seymouria/message/2680) I could not
find a lot of info on this fossil so take and date ranges of this fossil with a grain of salt.
Pakicetus:
55.8 MYA (Pakicetus - Wikipedia).
Ichthyolestes:
48.6 MYA (Ichthyolestes - Wikipedia).
Gandakasia:
??????????
Ambulocetus:
50 MYA (Ambulocetus - Wikipedia).
Himalayacetus:
55.8 MYA (Himalayacetus - Wikipedia).
Dalanistes:
48.6 MYA (Dalanistes - Wikipedia).
Rodhocetus:
47 MYA (Rodhocetus - Wikipedia).
Takracetus:
45 MYA (Takracetus - Wikipedia).
Gaviacetus:
45 MYA (Gaviacetus - Wikipedia).
Dorudon:
41 MYA (Dorudon - Wikipedia).
Basilosaurus:
40 MYA (Basilosaurus - Wikipedia).
Mystecetes:
39 MYA (Baleen whale - Wikipedia).
I could not find much on odontocetes.
If you just look at the most common speciments, Pakicetus, Ambulocetus, Rodhocetus, Dorudon, Basilosaurus, and Mystecetes, you definitely see this evolutionary trend.
http://www.nature.com/...al/v413/n6853/images/413259aa.2.jpg.
When questioning whether evolution could have evolved whales, keep in mind that human evolution took only 6 million years.

This message is a reply to:
 Message 43 by herebedragons, posted 01-10-2012 9:55 AM herebedragons has replied

Replies to this message:
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dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


Message 58 of 443 (648124)
01-13-2012 10:58 AM
Reply to: Message 45 by TheArtist
01-12-2012 3:13 PM


quote:
According to wikipedia "Himalayacetus is an extinct genus of carnivorous aquatic mammal (from the same link you provided).
This aquatic mammal was one of the earliest mammals on your list, alongside Pakicetus and even the Pakicetus seemed to roam dry land.
What is your thoughts around this?
Keep in mind that there are a few factors that make the fossil record imperfect.
As you see, each species is only a side-branch off the family tree, and may have added unique characteristics after it split off. If those unique characteristics (of a primitive form) are similar to those of more evolved forms (more whalelike), then we are seeing convergent evolution. Lets say that Pakicetus splits off from the line of species leading up to whales. Further forms of Pakecitus hypothetically evolve more whale-like forms, but then eventually die out. This is convergent evolution. It makes it seem as if more advanced species appeared earlier.
Also notice that more primitive forms can exist along-side more advanced forms. E.g. bacteria are still around even when they evolved before mammals.
Another fact is that sometimes a fossil is placed in slightly wrong strata e.g. a deer dies in a pit that contains strata that is 5 million years old. Sometimes the dating method is off (sometimes by 5%).
Sometimes we may not have a 100% accurate representation of a species morphology so it may really be more primitive or more advanced than it appears. Sometimes we may not have an accurate view of when a species has been around because we have not found all the fossils yet. E.g. Pakecitus may actually have started at 65 million years ago, not 55 million years ago (making it earlier than Himalayacetus), and we may just not have found the oldest fossils yet.
Some species may not be the earliest representative of their step in evolution. E.g. Pakecitus may be not be the earliest representative of its evolutionary grade, and it may have an ancestor very much like it that precedes Himalayacetus, and Pakecitus is only a primitive species that has survived to live along-side more advanced ones.
So this tends to fuzzy up the evolutionary trend, but we still usually tend to see a trend.
If you take a look at the graph herebedragons made in message 43, we still see a general statistical trend from more primitive to more advanced.
Here are some articles about it.
Here is an article by the people who found the fossil.
Just a moment...
Here is another description of the fossil.
Found from Jaw bone.
As you see from this source, it is only known from a few jaw remnants.
Thylacosmilus - Facts and Pictures
Here is another discussion of this fossil.
http://www.sciencenews.org/sn_arc98/10_10_98/fob3.htm
Since we know very little about this controversial fossil, lets not use it to mess up whale evolution.

This message is a reply to:
 Message 45 by TheArtist, posted 01-12-2012 3:13 PM TheArtist has not replied

  
dan4reason
Junior Member (Idle past 4142 days)
Posts: 25
Joined: 01-03-2010


Message 63 of 443 (648322)
01-14-2012 1:27 PM
Reply to: Message 46 by herebedragons
01-12-2012 3:19 PM


quote:
Evolution could happen because evolution did happen? Circular reasoning.
My question is not so much "could" it happen as "did" it happen. I am not questioning evolution in the traditional sense. I am only trying to make sense of it. For the most part I accept evolution, but I don't just "believe" because of a well placed "series". I need to examine it and decide for myself if the evidence is sufficient. That's what we should all be doing, correct?
This is what you said: "Could evolution have caused such rapid changes among contemporary species?"
So you were asking whether evolution COULD happen in such a short period of time (if whale evolution did take a short period of time), and I answered it. By now claiming that my answer is insufficient because it does not show that evolution DID happen, is artificially moving the goal posts.
A well-placed series is a strong confirmation of the predictions of evolution. Looking at the family tree produced by comparing the genes of different organism, we know that whales most likely evolved from land mammals. The fact that we find transitionals at all is evidence for evolution, the fact that we find them in a general series, before we see whales makes it even stronger. It confirms the predictions evolution makes, and totally makes sense if evolution is true.
However, a well-placed series is not the only evidence for whale evolution. Vestigial body parts, the cattle rumen in the stomach, atavistic body parts, and embryonic body parts also support evolution.
quote:
True. But those dates don't necessarily tell you when the species started, only when that particular animal lived. Can it be logically deduced that was one of the earliest specimens? Especially when a sister group is significantly older.
Right, they are only approximations, which is one reason why, if evolution is true, we see only a general trend from less whale-like to more whale-like, especially when we leave out species we don't have a lot of data on. However, it is still the best approximation we have, and see still see a trend.
quote:
I also question using Wikipedia as a source. It is just not reliable.
That statement in itself is not reliable. Wikipedia is mostly reliable, and most of its mistakes are minor. So can you present the sources that YOU used?
quote:
I am also uncertain as to why these creatures would be adapting more and more to life in the water when India was crashing into the continent, closing the Tethys and pushing up the himalayas. Any insights here?
Continental drift takes long periods of time, so whales still had a large area to evolve in. Plus you are assuming that whales did not diversify to areas different than where the Indian subcontinent was meeting Asia.

This message is a reply to:
 Message 46 by herebedragons, posted 01-12-2012 3:19 PM herebedragons has replied

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